The present invention relates to a method for fabricating a semiconductor device, and more particularly, to a method for fabricating a capacitor in a semiconductor device.
Due to the large integration scale of semiconductor devices, the minimum line width is becoming smaller and the scale of integration is becoming greater. Consequently, the area on which a capacitor is to be formed is also becoming smaller. However, a capacitor in a cell generally needs to secure a high level of capacitance which is required in each cell even though the size of the area for forming a capacitor is becoming smaller. Thus, a method for fabricating a cylinder type capacitor wherein a sacrificial layer between capacitors is removed has been introduced.
Meanwhile, barrier metals are used to reduce a contact resistance and improve adhesion to bottom layers when forming a bottom electrode.
However, as the large scale integration continues to improve, the bottom size of a capacitor also continues to decrease. Consequently, the size of the contact area with a bottom storage node contact plug decreases, resulting in limitations in reducing the contact resistance.
Furthermore, a titanium layer, which is often used as barrier metals, shows an insufficient level of deposition capacity toward the bottom area. Thus, it is difficult to improve a contact resistance (Rc).
Moreover, after a barrier metal and a conductive layer are formed, residues of the barrier metal may remain after an isolating etch process is performed for forming a bottom electrode. Thus, bridges between capacitors may occur due to such residues. If a supporting layer is formed to prevent a collapse of a bottom electrode during a dip out process, more bridges may occur between capacitors because of the residues.